 
 (s/defschema ValidTime
   "See http://stixproject.github.io/data-model/1.2/indicator/ValidTimeType/"
-  {(s/optional-key :start_time) Time
-   (s/optional-key :end_time) Time})
+  {(s/optional-key :start_time)
+   (describe Time "If not present, the valid time position of the indicator does not have a lower bound")
+   (s/optional-key :end_time)
+   (describe Time "If not present, the valid time position of the indicator does not have an upper bound")})
 
 ;;Allowed disposition values are:
 (def disposition-map


(s/defschema Contributor
  "See http://stixproject.github.io/data-model/1.2/cyboxCommon/ContributorType/"
  {(s/optional-key :role) s/Str
   (s/optional-key :name) s/Str
   (s/optional-key :email) s/Str
   (s/optional-key :phone) s/Str
   (s/optional-key :organization) s/Str
   (s/optional-key :date) Time
   (s/optional-key :contribution_location) s/Str})

(s/defschema RelatedIdentity
  "See http://stixproject.github.io/data-model/1.2/stixCommon/RelatedIdentityType/"
  {(s/optional-key :confidence) v/HighMedLow
   (s/optional-key :information_source) s/Str
   (s/optional-key :relationship) s/Str ;; empty vocab
   :identity Reference ;; Points to Identity
   })

(s/defschema Identity
  "See http://stixproject.github.io/data-model/1.2/stixCommon/IdentityType/"
  {:description s/Str
   :related_identities [RelatedIdentity]})

(s/defschema Activity
  "See http://stixproject.github.io/data-model/1.2/stixCommon/ActivityType/"
  {:date_time Time
   :description s/Str})

(s/defschema Observable
  "A simple, atomic value which has a consistent identity, and is

(s/defschema Tool
  "See http://stixproject.github.io/data-model/1.2/cyboxCommon/ToolInformationType/"
  {:description s/Str
   (s/optional-key :type)
   (describe [v/AttackToolType] "type of the tool leveraged")
   (s/optional-key :references)
   (describe [s/Str] "references to instances or additional information for this tool")
   (s/optional-key :vendor)
   (describe s/Str "information identifying the vendor organization for this tool")
   (s/optional-key :version)
   (describe s/Str "version descriptor of this tool")
   (s/optional-key :service_pack)
   (describe s/Str "service pack descriptor for this tool")
   ;; Not provided: tool_specific_data
   ;; Not provided: tool_hashes
   ;; Not provided: tool_configuration
